package Q3;

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class Main {

    public static int n;
    public static int[] arr;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        n = scanner.nextInt();
        arr = new int[n];
        Map<Integer, Integer> map = new HashMap<>(); //key 为 arr 中的元素，value 为元素的个数
        for (int i = 0; i < n; i++) {
            arr[i] = scanner.nextInt();
            map.put(arr[i], map.getOrDefault(arr[i], 0) + 1);
        }

        Set<Integer> keySet = map.keySet();


    }
}
